Excel LAMBDA for taking a range of repeated columns, trimming each set and stacking them on top of each other

excel-lambda-StackEveryNColumns.txt

/*
For a single data with sets of 'every' columns with differing counts of rows, 
trim each set and stack them on top of each other

Dependencies:
STACKER:
https://gist.github.com/ncalm/ef7ed953571eec1475c291948aa2dbc3

EveryXtoN:
https://gist.github.com/ncalm/48b96ac45685a7897fdf0a7336b2e96b
*/
StackEveryNColumns = LAMBDA(data, every, [header], 
    LET(
        i, EveryXtoN(COLUMNS(data), every),
        fn, LAMBDA(b, TRIMRANGE(CHOOSECOLS(data, b + SEQUENCE(, every, 0)))),
        stacked, VSTACKER(fn)(i),
        IF(ISOMITTED(header),stacked,VSTACK(header, stacked))
    )
);